Optimization of the double pump-probe technique: decoupling the triplet yield and cross section

Area of Science:

• Photochemistry
• Spectroscopy
• Physical Chemistry

Background:

• The standard pump-probe technique is limited in determining excited-state parameters.
• The double pump-probe technique (DPP) was developed to overcome these limitations.

Purpose of the Study:

• Investigate the advantages and limitations of the DPP.
• Determine the influence of experimental parameters on DPP accuracy.
• Develop an analytical model for DPP analysis.

Main Methods:

• Theoretical and experimental investigation of the DPP.
• Application of an analytical model for both reverse saturable and saturable absorption.
• Analysis of excitation wavelength and pump fluence effects.

Main Results:

• DPP accuracy improves with increased triplet state population.
• The saturable absorption regime optimizes DPP performance.
• Tuning excitation wavelength or increasing pump fluence can enhance accuracy, but the former avoids photodegradation.

Conclusions:

• The DPP accurately separates triplet yield and excited-state absorption cross sections.
• Optimizing DPP in the saturable absorption regime is recommended.
• The technique allows for accurate characterization of excited-state dynamics.